Pregermination of botanic seed (a.k.a. priming, osmoconditioning, vigorizing, chitting) is a seed treatment by which early seed germination events up to, and sometimes including, radicle emergence are initiated under optimal conditions. The results of this pregermination treatment are that treated seeds often emerge more quickly and to a higher percentage than untreated or raw seeds under less than ideal environmental conditions (see M. Rivas, F. V. Sandstrom, and R. L. Edwards, "Germination and Crop Development of Hot Pepper after Seed Priming," HortScience, 19:279-281, 1984; D. J. Cantliffe, J. M. Fischer, and T. A. Nell, "Mechanism of Seed Priming in Circumventing Thermodormancy in Lettuce," Plant Physiology 75:290-294, 1984). According to several prior methods, after pregermination, the seeds are then either redried or planted immediately, usually under less than optimal environmental conditions. According to the instant invention, pregermination is accomplished in hydrated gel capsules, avoiding the shortcomings of prior art methods. The use of a capsule which contains sufficient free water to participate in the physiological processes of pregermination provides advantages over known methods of delivery.
At least two methods of delivering pregerminated seeds are known: hydration and redrying of raw seeds, and fluid drilling techniques. In the first method, seeds are hydrated in a solution of water alone, or water containing an osmoticum such as salt or polyethylene glycol for periods of time ranging from twenty-four hours to several days (see, A. A. Kahn, "Preconditioning, Germination and Performance of Seeds," p. 283-316, in "The Physiology and Biochemistry of Seed Dormancy and Germination," edited by A. A. Kahn, North-Holland Publishing Co., Amsterdam and N.Y. (1977)). After hydration but before radicle emergence, the seeds are removed from the pregermination solution and dried under various conditions. The pregerminated seeds are sown in the field or greenhouse in the same fashion as are untreated raw seeds. This method of pregermination and delivery has several drawbacks. First, the delicate hydrated seeds must be manipulated several times. This may lead to seed damage resulting in a reduced seed lot germination. This problem is greatly increased if any radicle emergence occurs prior to redrying. Secondly, the redrying process results in additional costs for increased handling, equipment, and energy inputs. Thirdly, the redrying process introduces the need for the primed seeds to be rehydrated when placed into any growth medium. This additional step could result in delayed emergence or increased susceptibility to soil pathogens.
The second previously known method for delivering pregerminated seeds is fluid drilling. In fluid drilling, seeds are first either pregerminated in water or an osmoticum as described above. Then, the seeds are added to a fluid drilling matrix such as Laponite in water or Agrigel in water. Finally, wet slurry of the seeds in a fluid drilling matrix is then delivered to the growing area. (See, D. Gray, "Fluid Drilling of Vegetable Seeds," Horticultural Reviews, p. 1-27, 1981). This method has at least three major drawbacks. First, the seeds are placed randomly in the fluid drilling matrix reducing the possibilities for precision planting. Secondly, the seeds are subject to handling after radicle emergence and root growth up to 1 to 2 cm which may result in increased root damage and loss of seedling viability. Thirdly, fluid drilling techniques require special equipment.
The basis for this invention lies in a method for providing for seed pregerminaton after encapsulation. This is accomplished by using a hydrated polymer gel as the encapsulant. The free water contained within the capsule is capable of participating in the pregermination process.
This unique method of pregermination in a gel capsule has the following advantages. It avoids the step of re-drying the seeds. Encapsulation in a hydrated polymer also allows singulation in a seed-sized capsule or pellet that can be precision drilled, eliminating one drawback of the fluid drilling method. Finally, encapsulation and pregermination can be controlled to prevent seed radicle emergence prior to planting. The instant technique also affords the possibility of safely handling the seeds, even after the radicle has emerged.
Additionally, this method of encapsulation and pregermination allows for the timely and effective delivery of a large number of useful additives which include but are not limited to fungicides, insecticides, nematicides, fertilizers, growth promoting agents, growth regulators and beneficial microorganisms, including but not limited to bacteria, fungi, nematodes, and actinomycetes.
Thus, an objective of this invention is to enable pregermination of botanic seeds in a hydrated, polymer gel capsule which results in more rapid and more uniform emergence of a greater percentage of seedlings from any growth medium.
Another objective of this invention is to enable the delivery of hydrated, pregerminated seeds to eliminate the need to dry and then to rehydrate the seeds in the growth medium.
A further objective of this invention is to provide singulated, pregerminated seeds to permit precision delivery of pregerminated seed to any growth medium.
A still further objective of this invention is to enable the delivery of pregerminated seeds in hydrated gel capsules along with a wide range of useful chemical and biological additives to further improve the performance of the seeds under a wide range of abiotic and biotic conditions.
A final objective of this invention is to control radicle emergence of pregerminated, hydrated seed, and also, to protect from damage any emerged radicles.